Question

You're at a Starbucks coffee shop in Chicago on a cold winter day. You get a large cup of hot coffee and a small cup of room temperature liquid creamer on the side. At one point in this process before you take your first sip, you will add the creamer to the coffee cup. If you want to maximize the temperature of the coffee by the time you sit down at your desk, do you add the creamer before you leave the coffee shop or after (when you're at your office desk)?

a) Before leaving the coffee shop
b) After reaching the office desk
c) It doesn't matter
d) Not enough information provided

Answer 1

To maximize the temperature of coffee, add the room-temperature creamer before leaving the coffee shop. This slows down the cooling process due to a smaller temperature difference between the coffee-creamer mixture and the surrounding air.

Step-by-step explanation:

If you want to maximize the temperature of the coffee by the time you sit down at your desk, you should consider the rate at which coffee cools down. According to Newton's Law of Cooling, a hot object cools down faster when the temperature difference between the object and its surroundings is larger. This implies that by adding room-temperature creamer sooner, the temperature difference between the coffee-creamer mixture and the surrounding air is reduced, so the coffee will cool down more slowly when compared to waiting until you reach your office desk. Therefore, the best choice is to add creamer before leaving the coffee shop.

This situation illustrates the fact that the rate of heat transfer from an object to its environment depends on the difference in temperatures between them. The sooner you add the creamer, the smaller the temperature difference becomes, and hence the slower the rate of cooling for the coffee-creamer mixture during your travel to the desk.